The behaviour of soldiers who used an image of Labour leader Jeremy Corbyn for target practice is "alarming and unacceptable", a party spokesman has said.
In the wake of the video being shared on social media - showing personnel shooting at a picture of Mr Corbyn - the Army has confirmed an investigation has been launched.
The footage captured in Kabul, Afghanistan, shows personnel from 3rd Battalion, Parachute Regiment using the Islington North MP for target practice on a Simunition range.
In response, a Labour party spokesman, said: "This behaviour is alarming and unacceptable. We have confidence in the Ministry of Defence to investigate and act on this incident."
An Army spokesman said they are aware of the video circulating on social media.
"This behaviour is totally unacceptable and falls well below the high standards the Army expects, a full investigation has been launched," he added.
The video shows a number of soldiers taking aim down the range and firing their weapons - the camera then focuses on the target and zooms in on an image of Mr Corbyn.
With a graphic of "happy with that" across the screen throughout, a number of marks can be seen peppered across Mr Corbyn's face.
It is understood it was a non-lethal hardened wax substance aimed and fired at the image instead of metal bullets, with the incident taking place in the past few days.
The range is designed for and used by personnel to practise what is called the "guardian angel drill" - a force protection tactic.
Shadow defence secretary Nia Griffith slammed the video on Twitter, describing it as "shocking and completely unacceptable".
"Right that the Army is carrying out a full investigation," she added.
Former soldier and Tory MP, Johnny Mercer, tweeted that "every organisation has good people who make serious misjudgements".
He added: "It's how it police's itself that matters, and an inability to do that correctly has caused so many problems of late (IHAT). I look forward to a robust response."
Labour MP, Dan Jarvis, who is also a former Paratrooper, said the incident is "shameful and utterly unacceptable".
"This goes against the values and standards of the British Army. I welcome the Ministry of Defence investigation into this video and trust it will be resolved quickly," he added.
Shadow education secretary, Angela Rayner, also criticised the video branding it as "absolutely disgraceful".
She added: "I hope the investigation will be conducted thoroughly and the conclusions made public.
"Political tensions are heightened at the moment and this type of behaviour is wholly inappropriate and unacceptable, we expect much better from our Army and soldiers."
Labour MP Lucy Powell said she is "absolutely shocked", and that the behaviour of the personnel is a "total disgrace and utterly unacceptable".
"Not least emerging the day after someone was convicted of trying to murder an MP," she added.
It comes after far-right activist Tommy Robinson posted a photograph of himself surrounded by grinning soldiers in October - prompting another Army probe.
The former English Defence League leader also shared a video featuring Army personnel who cheered and shouted his name.
At the time, the Army said it was aware of the image and footage and was "investigating the circumstances", adding that a "far-right ideology is completely at odds with the values and ethos of the armed forces".